Method for treating a diamond surface and corresponding diamond surface

ABSTRACT

The invention relates to a treatment method of a diamond surface and to a corresponding diamond surface ( 5 A).  
     According to the method, ions are produced, each having at least three positive charges, and a beam of these ions is sent towards a diamond surface in order to make at least one zone of the surface conductive under the effect of said ions. Advantageously, conductive islands ( 6 ) are formed with a diameter smaller than 150 nm, then used preferably as one election tank (diameter smaller than 10 nm) or as replenishment reservoirs for cold cathodes.  
     Application to micro-electronics and to the production of cold cathodes.

[0001] This invention relates to a surface treatment method wherein:

[0002] ions are produced, each having at least three positive charges,and

[0003] a beam of these ions is sent to the surface.

[0004] The invention also relates to a corresponding diamond surface andto applications of such method or of such surface.

[0005] A method of the type mentioned above has been described in theinternational applications WO-98/29901 and WO-98/54747.

[0006] More precisely, the document WO-98/29901 relates to a structuremodification without the ions contacting a surface of a semi-conductor,in order to create insulating zones in this surface.

[0007] The document WO-98/54747 describes, for its own part, an ionetching technique. In a particular embodiment disclosed in this document(see claim 8), the beam is sent towards a semi-conductor or aninsulating material and the electrical or chemical nature or thetopography of the surface is modified locally by such beam, without thebeam contacting the surface.

[0008] This invention concerns a technique enabling to form conductivezones on an insulating surface, thereby surprisingly causing only an ionbeam to be sent. The invention concerns such a technique enabling toform such controllable and small-sized zones.

[0009] The invention therefore relates to a treatment method of aninsulating surface enabling to make at least one zone of this surfaceconductive, implementing against all odds the sending of an ion beamtowards the surface.

[0010] The invention also concerns an insulating surface delineatingconductive islands with a diameter smaller than 10 nm, which can beobtained by the treatment method of the invention.

[0011] The invention also relates to applications of this technique tomicroelectronics, for the realisation of one election tanks, and to theproduction of cold cathodes, notably for flat screens.

[0012] To this effect, the purpose of the invention is a surfacetreatment method wherein:

[0013] ions are produced, each having at least three positive charges,and

[0014] a beam of these ions is sent to the surface.

[0015] According to the invention, the beam is sent towards a diamondsurface, in order to make at least one zone of the surface conductiveunder the effect of these ions, each ion having a charge, a kineticenergy and an incidence such that it generates local structuralmodifications of the surface, each having a surface area greater than 4atomic surfaces and preferably 10 atomic surfaces, of said diamond andsmaller than 22,500 nm².

[0016] By “diamond” is meant not only a natural or artificial diamond(prepared for example by a CVD—Chemical Vapour Deposition—or HPHT (HighPressure High Temperature—method), polycrystalline or monocrystallinediamond, but also an “amorphous carbon sp3” (diamond like carbon), whichhas a link sp3 like diamond, but another crystallographic structure. Thediamond surface is advantageously prepared as a thin layer on asubstrate made of silicium preferably.

[0017] It is particularly surprising that sending an ion beam towards aninsulating surface, composed of diamond (i.e. pure crystallised carbonin a diamond structure) may cause local stable formation of conductivezones. This effect is due to a physical phenomenon unexplored so far,according to which the structure of the diamond can be modified over asmall surface into a conductive allotropic variety, by one or severalsingular ions. Indeed, carbon exhibits several crystalline allotropicshapes comprising notably diamond (insulating form) and graphite(conductive form), and one ion having at least three positive charges iscapable of causing in a diamond surface a large defect with respect toatomic dimensions, but small in size macroscopically. Such an iongenerates within the diamond surface massive excursion of electronsenabling to obtain this result.

[0018] By contrast, for example, the technique described in the documentWO-98/54747 rests on the expulsion of atoms present in the molecules ofthe surface in question (see in particular page 8, lines 7-19) and istherefore very different in its purpose and in its application of themethod of this invention.

[0019] The operations with the ion beams are performed preferably undervacuum. Thus vacuum may correspond to relatively high pressure, forexample in the order of 10⁻⁹ Pa. It may also be an ultra-vacuum.

[0020] The ions, each having at least three positive charges, are calledmulti-charged positive ions. The monocharged ions, for example, cannotproduce the effect specified, consisting in the local creation of stableconductive zones at the surface of the diamond. Very energeticmonocharged ions could a priori break locally crystallographic orchemical links when passing through any material. However, they wouldcreate only punctual surface defects in the order of atomic dimensions.Such depth defects of punctual surface do not enable to use conductivezones created. Notably, the defects produced have a tendency to berepaired naturally by thermal effects, so that later chemical treatmentwould be necessary to realise a stable conductive zone.

[0021] The conductive zones formed have conductive properties similar tothose of graphite, which is explained by the structural modification ofthe diamond in order to change it into another non-diamond allotropicvariety, characterised in particular by a loss of the crystalline natureof the diamond.

[0022] The method above is applicable to the formation of very smalllocal conductive zones, such as conductive islands having a diametersmaller than 150 nm and preferably smaller than 10 nm, to the formationof conductive lines or of portions of conductive surfaces or to thestructural modification of the whole surface of diamond.

[0023] The conductive zone generated by the impact of one of the ions ofthe beam has a determined surface and a determined depth on a diamondsurface given by the charge, the kinetic energy and possibly theincidence of the ion.

[0024] By contrast, the monocharged ions can individually produce onlydefects with a surface area smaller than 10 atomic surfaces, and themassive sending of an ion beam can only lead to conductive surfaces muchgreater than 22,500 nm².

[0025] Below, by ‘local structural modification’ is meant a modificationover a surface area in the range specified above.

[0026] In a first preferred embodiment with a local structuralmodification the beam is sent in order to form at least one conductiveisland with a diameter smaller than 150 nm.

[0027] Advantageously, the conductive islands have a diameter smallerthan 10 nm and preferably ranging between 2 and 6 nm. The treatmentmethod of the invention provides such an accurate local structuralmodification, each of the ions being able to form an island.

[0028] Then, the conductive islands are used preferably as one electiontanks. Said dots are particularly useful for their applications inmicro-electronics.

[0029] In another example of this first embodiment, conductive islandsare used as replenish reservoirs for cold cathodes. The size of theconductive islands is then advantageously greater than 10 nm, and stillpreferably greater than 100 nm.

[0030] According to a second preferred implementation, the beam is sentin order to form conductive lines delineating insulating patterns.

[0031] According to a third preferred embodiment, the beam is sent inorder to make at least one fraction of the diamond surface conductive.

[0032] To do so, one resorts advantageously to a local structuralmodification of these surface fractions caused by a sweeping beam. Thisenables an accuracy corresponding to the dimension of the beam and toits guiding, i.e. conventionally smaller than one micron.

[0033] In a particular example of this third embodiment, the wholediamond surface is made conductive.

[0034] According to a preferred embodiment of local structuralmodification, said modification is performed at random. Thus, inparticular, the first embodiment then consists in forming conductiveislands distributed at random over the diamond surface, the number ofconductive islands by surface unit being defined by the number of ionsreaching this surface.

[0035] In another embodiment of local structural modification, saidmodification is performed along a preset scheme.

[0036] In particular, advantageously, the zones of the surface aretreated selectively while sending the beam towards guiding means, whiledirecting the beam towards the surface with the guiding means, and whileperforming repeatedly the following operations:

[0037] space-time detection of ion interactions of the beam with thesurface,

[0038] interruption of the beam,

[0039] relative displacement of the surface in relation to the positionof the beam, and

[0040] reestablishment of the beam.

[0041] The relative displacement of the surface with respect to theposition of the beam may imply a displacement of the surface or adisplacement of the beam, by variation of their position or of theirorientation. Then the local structural modification takes place insuccession, zone after zone. In an embodiment variation, several beamsare directed simultaneously towards the surface.

[0042] Space-time detection consists in identifying the positions aswell as the moments of the interactions.

[0043] Proceeding in such a way enables to control the durations ofexposure of the diamond surface and the relative displacements of thissurface with respect to the ion beam. Such control provides very highreliability. Indeed, the local structural modification by ions impliesrandom arrival of the ions on the target, from a spatial as well as atime-related viewpoint. The controlled local structural modificationmethod as specified above enables to adjust the treatment to theserandom phenomena.

[0044] The international application WO-98/54747 contains a detaileddescription of several embodiments of such a method. All theseembodiments are applicable to this invention, whereas the control oflocal structural modification of this state of the art is combined withthe selection of a diamond surface and the use of ions each having atleast three positive charges.

[0045] In particular, the following characteristics are implementedadvantageously; separately or in all their technically possiblecombinations:

[0046] the ion beam between the ion source and the surface to be treatedis localised spatially, preferably by means of one or several beamcollimators,

[0047] the position of the beam is controlled and is cooled down,

[0048] monokinetic selection of the ions between the ion source and thesurface to be treated is performed,

[0049] the beam is interrupted by means of application of en electricalfield substantially parallel to the surface to be treated,advantageously in combination with the use of a collimator,

[0050] the guiding means comprise means of application of a magneticfield, deviating the ion beam by a certain angle, this magnetic fieldbeing preferably uniform and the angle of deviation preferably 90°,

[0051] the guiding means comprise means of application of an electricalfield generating an electrical deviation,

[0052] the guiding means implement simultaneously a magnetic field andan electrical field combined, for example in a Wien filter,

[0053] the surface is moved with respect to the position of the beam bymeans of at least one element selected among a piezoelectric quartz anda ceramic, moving the diamond surface with respect to the ion beamincident on this surface,

[0054] the surface treated is checked for local topography and/orelectrical conductivity, preferably by means of a tunnel effect and/oratomic force microscope,

[0055] interaction of the ions with the surface to be treated withoutany contact between the beam and the surface, the space-time detectionthen comprises a detection technique selected among the following:

[0056] measurement of photons emitted during the passages of electronsextracted from one electronic layer of hollow atoms of the ion beam toanother layer (preferably measurement of X-rays emitted),

[0057] detection of electrons emitted by Auger effect by the hollowatoms,

[0058] detection of the ions or hollow atoms properly speaking(preferably position, speed and charge of the backscattered hollowatoms),

[0059] detection of ionised fragments of molecules of the treatmentsurface expelled under the effect of the interactions (separated atoms),

[0060] detection of a sheaf of electrons emitted under the effects ofthe interactions,

[0061] measurement of photons emitted by atoms from the diamond surface,and

[0062] combination of several of these techniques.

[0063] The treatment method may imply remote interaction, by a potentialeffect, and/or an interaction with contact of the ion beam and of thediamond surface, liable to cause the penetration of the ions below thesurface (kinetic effect).

[0064] Thus, in a first preferred interaction embodiment, the ion beamis sent so that it contacts the surface and penetrates it. So, the ionswith an initial kinetic energy ranging between 5 eV/q and 500 keV/q aregenerated advantageously.

[0065] In a second interaction embodiment, the beam is applied adeceleration voltage close to the surface in order to confer to the ionsof the beam a controlled average speed, whereas the ions extractelectrons from the diamond atoms without contacting the surface andtherefore modifying the links between these atoms.

[0066] Then, the ions are slowed down advantageously so that they haveclose to the surface a kinetic energy ranging between 5, 10⁻² eV/q and 5eV/q.

[0067] This contact free interaction technique is described in detail inthe international application WO-98/54747, in the case of an etchingcontrol, and in the international application WO-98/29901, for theformation of insulating zones on a semi-conductive surface. All thesetechniques disclosed and developed in both these previous applicationsmust be transposed to this application, with the following adjustments:as regards the application WO-98/54747, the method must be specified fora beam of multicharged ions and a diamond surface. Besides, the currentmethod is not limited to the control technique of local structuralmodification described in this previous application and is valid inparticular for a random etching process. As regards the documentWO-98/29901, the treatment method is applied to a diamond surface and,thus, conductive zones are produced on an insulating zone and notinsulating zones on a semiconductive surface.

[0068] According to a third interaction embodiment, the ions touch thesurface, but without any violent shock, so that they cannot penetratethe surface and interact only in the uppermost portion of this surface.

[0069] In the third embodiment, the ions are slowed down advantageouslyuntil they reach a level of energy respectively smaller than 5 eV/q and25 eV/q.

[0070] In a first advantageous embodiment of the diamond surface, saidsurface is a monocrystalline, artificial or natural diamond surface.

[0071] In a second advantageous embodiment, it is a polycrystallinediamond surface, preferably obtained by a CVD (Chemical VapourDeposition) or a HPHT (High Pressure High Temperature) method. Thediamond surface is then advantageously a layer deposited on a substrate,for example silicium.

[0072] The use of a polycrystalline diamond surface having monocrystalsof various sizes, preferably CVD or HPHT, enables advantageously toincrease the number of electrons available. Indeed, such a realisationenables to modify the fraction of the crystalline surface with respectto grain joints which are conductive, said joints being able to supplymore electrons to their insulating neighbours.

[0073] The irradiation technique of such a surface also enables tocontrol the conductive surface/insulating surface ratio a posteriori andin an industrially easy fashion.

[0074] These implementations with monocrystals of various sizes areparticularly interesting for the production of cold cathodes, since theyprovide a replenishment with electrons.

[0075] In a third advantageous embodiment, this surface is an amorphouscarbon sp3 surface.

[0076] Advantageously, the diamond surface is passivated by an atomicmonolayer, preferably made of hydrogen or oxygen. This monolayer can beconductive, for example hydrogen, or insulating (example: oxygen). Inanother embodiment, the diamond surface is natural.

[0077] The invention also relates to a diamond surface delineatingconductive islands with a diameter greater than 2 and preferably than 3atomic distances and smaller than 10 nm, and preferably ranging between2 and 6 nm.

[0078] The islands have advantageously conductive properties similar tothat of graphite.

[0079] Such a surface can notably be obtained by the treatment method ofthe invention.

[0080] The invention also relates to the application of such a surfaceto microelectronics, wherein one uses the conductive islands as oneelection tanks.

[0081] The invention also relates to the application of the treatmentmethod for the production of cold cathodes, notably for flat screens.

[0082] The invention will be illustrated and better understood usingembodiments and modes of realisation of the invention specified belowwith reference to the appended drawings, wherein:

[0083]FIG. 1 shows a silicium wafer covered with a diamond layer;

[0084]FIG. 2A shows the wafer of FIG. 1 after application of the methodof the invention according to a first embodiment;

[0085]FIG. 2B shows the wafer of FIG. 1 after application of the methodof the invention according to a second embodiment;

[0086]FIG. 2C shows the wafer of FIG. 1 after application of the methodof the invention to a third embodiment;

[0087]FIG. 3 is a flow chart of the different steps of the methodaccording to the invention with controlled local structuralmodification, enabling to obtain a wafer such as that of FIG. 2A andFIG. 2B;

[0088]FIG. 4 represents an embodiment of a structural modificationdevice enabling notably to apply the method with controlled localstructural modification, whereof the main steps are schematised on FIG.3; and

[0089]FIG. 5 represents the interaction of a multicharged positive ionwith the surface of the wafer of FIG. 1, during the application of themethod according to the invention.

[0090] A wafer 1 (FIG. 1) comprises a substrate 2 of silicium coveredwith a diamond layer 3 deposited on the substrate 2. The layer 3, havinga thickness e for example ranging between 1 and 500 μm, is passivated bya hydrogen or oxygen monolayer 4. The layer 3 thus defines a surface 5,which represents the superficial portion of the wafer 1 occupied by thediamond layer 3. The diamond being a very good electrical insulatingmaterial, The layer 3 is very insulating under the monolayer 4.

[0091] The treatment method described below enables to transform thewafer 1 in three possible ways:

[0092] into a wafer 2A whereon the surface 5A comprises a diamond layer10A fitted with conductive islands 6 with very small sizes, smaller than150 nm, advantageously smaller than 10 nm and preferably ranging between2 and 6 nm (FIG. 2A);

[0093] into a wafer 2B having a surface 5B comprising a diamond layer10B wherein are drawn conductive lines 7 delineating insulating patterns8 (FIG. 2B); or

[0094] into a wafer 2C having a surface 5C comprising a diamond layer10C wherein are formed conductive surface fractions 9 (FIG. 2C).

[0095] The first two realisations (wafers 2A and 2B) correspond to localselective surface treatment, whereas the third realisation (wafer 2C)can also be obtained by a local structural modification. A particularcase of the third realisation is that whereon the surface is treatedentirely. One of the extremely interesting particularities of the wafers2A, 2B and 2C (apart from the treatment of the whole surface 5) is thatvery conductive zones, whereof the dimensions can be controlledperfectly, are close to very insulating zones. More precisely, theconductive islands 6 or the conductive lines 7, as well as the surfacefractions 9, have electrical properties similar to those of graphite.According to the treatment methods leading to the wafers 2A, 2 b andpossibly 2C, a first embodiment of random local structural modificationis advantageous very fast and a second embodiment of local structuralmodification, controlled spatially, is advantageously accurate.

[0096] The realisation of wafers of the type 2A is particularlyinteresting in the field of the microelectronics, since the conductiveislands 6 whereof the diameter can be controlled sufficiently, can actas one election tanks. Information can be stored in the wafer 1according to the presence or not of an electron in each of these tanks.

[0097] The wafers of type 2A are also useful for the production of thecold cathodes. In such a case, the conductive islands 6 act asreplenishment reservoirs of such cold cathodes.

[0098] The treatment method of the surface 5 will now be detailed in aparticular embodiment, based upon the use of a specific local structuralmodification device represented on FIG. 4. This device enables to obtainany of the wafers 2A, 2B or 2C, enables random or spatially controlledtreatment and makes an interaction possible between a beam of ions andthe surface 5 with or without contact.

[0099] The local structural modification device comprises a source ofions 20 generating multicharged positive ions. The ion source 20 can usea preparation of the ions inside a very hot plasma confined in magneticstructures such as an ECR (Electron Cyclotron Resonance) source. It mayalso have as an operating principle the compression of electron beams ina solenoid, whereas atoms injected into the electron beam are ionisedand trapped by a space charge simultaneously. The ion source 20 can thusbe of the EBIS (Electron Beam Ion Source) type.

[0100] The ions emitted by the ion source 20 can be for instance argon,charged Ar¹⁷⁺ or Ar¹⁸⁺, oxygen or uranium. They can also be composed oflighter ions such as boron or carbon. The number of positive charges mayvary from a few units to 92 for uranium.

[0101] The ion source 20 thus generates an ion beam 41 according to afirst direction 51. The ions emitted have an initial kinetic energy inthe order of several keV/q, for instance ranging between 5 and 20 keV/q,q designating the number of positive charges of each of these ions.

[0102] The beam 41 is directed towards means for selecting a chosenionic specie, for example Ar¹⁷⁺. The selecting means consistadvantageously of first means of application 21 of a magnetic field 33,which comprises two opposite coils 31 and 32 or permanent magnets. Themagnetic field 33 is advantageously uniform. It can also be non uniformin order to be focussing. The magnetic field 33 is advantageouslyperpendicular to the direction 51 of the incident beam 41. The selectingmeans thus generate a beam 42 of the ions selected in a direction 52. Incontrolled etching, the ions of the beam 42 are preferably sent oneafter the other. In random etching, they are sent to different places,each of the ions being capable of producing a print on the surface 5 forthe formation of a conductive island 6.

[0103] In an embodiment variation, the selecting means are means ofapplication of an electrical field.

[0104] The local structural modification device comprises preferably adirect position control system of the beam 42, referred to as 22.

[0105] The local structural modification device comprises then means forinterrupting the beam 42, comprising advantageously an electronicallyoperated beam shutter 24. This shutter 24 is intended for interruptingthe beam 42 when a local structural modification is detected on thesurface 5.

[0106] In an embodiment variation, the shutter 24 is replaced with meansof application of an electrical field perpendicular to the direction 52of the beam 42, whereas the application and the withdrawal of thiselectrical field play respectively the part of closing and opening theshutter 24.

[0107] The beam 42 is directed towards guiding means, guiding the beam42 towards the surface 5 to be treated. These guiding means consistadvantageously of second means of application 23 of a uniform magneticfield 36, comprising two opposite coils 34 and 35 or permanent magnets.The magnetic field 36 being preferably perpendicular to the direction 52of propagation of the beam 42, thus directs the beam 42 in a direction53 towards the surface 5, preferably in normal incidence.

[0108] In an embodiment variation, the guiding means consist of means ofapplication of an electrical, static or pulsed, field.

[0109] Preferably, interrupting means of the beam are also availabledownstream of the coils 34 and 35.

[0110] The local structural modification device also comprises,advantageously, a spatial localisation system of the beam 42, consistingfor example of one or several collimators 25, 26. For great accuracytreatment, the collimators are nanometric.

[0111] The wafer 1 acting as a target is mounted on a translator 27,which enables movements along two directions 37 and 38 orthogonal to oneanother, and perpendicular to the direction 53 of the beam 42. Thetranslator 27 comprises for example two piezoelectric quartzes or twoceramics.

[0112] In the implementation with a contact free interaction, anelectrical field for deceleration of the ions of the beam 42 is appliedin the vicinity of the target, by biasing said target. This electricalfield decelerates sufficiently the ions of the beam 42 so that said ionsextract electrons from the surface 5 without any contact with thissurface and are backscattered in the form of hollow atoms.

[0113] This electrical deceleration field provides the ions with anenergy which can be as low as 0.025 eV/q, in a controlled fashion. Theelectrical field can be applied by means of a plane capacitor with apotentiometer.

[0114] In an embodiment variation, deceleration does not take place onthe target, by at some point of the beam line, by biasing the line.

[0115] The hollow atoms backscattered by the surface 5 form a beam 43,which goes into a direction 54 parallel to the direction 53 and inopposite direction to the beam 42. The beam 43 of hollow atoms goes thenthrough the collimators 25 and 26, the shutter 24 and the means ofapplication 23 of the magnetic field 36, in the example illustrated.This magnetic field 36 diverts the beam 43 in a direction 55, towards adetection surface 28.

[0116] The detection surface 28 gives the position, and advantageouslythe speed and the charge, of the hollow atoms of the incident beam 43.This detection surface 28 can be for example a grid of chaneltrons.

[0117] The local structural modification device also comprises a photonmeasuring device 49, notably for X rays, emitted when electrons leave anelectronic layer for another layer of the hollow atoms of the beam 43and/or hollow atoms formed in the surface 5.

[0118] Advantageously, the local structural modification device alsocomprises a detection system 45 detecting electrons emitted by Augereffect by the hollow atoms, etched hydrogen cores or atoms of the targetwhich have been expelled from the surface 5, a sheaf of emittedelectrons, photons emitted by atoms of the etching surface and/or anelectrical charge appearing on the target.

[0119] In a contact embodiment, but without any penetration of thesurface 5, the decelerating means are also present and actuated in theetching device. In another embodiment, with contact and penetration, thedecelerating means are suppressed or deactivated, or leave sufficientenergy to the ion beam 42 to penetrate the surface 5.

[0120] The beams 41, 42 and possibly 43 and the surface 5 of the wafer 1are preserved from the surrounding atmosphere by a vacuum enclosure. Thelocal structural modification device also comprises a treatment unit 29connected to the shutter 24, to the translator 27, to the detectionsurface 28, to the detection system 45 and to the measuring device 49.This treatment unit 29 receives signals from the detection surface 28,from the detection system 45 and from the measuring device 49, and iscapable of controlling the opening and the closing of the shutter 24 aswell as displacements of the translator 27.

[0121] The local structural modification device is preferably completedby a tunnel effect microscope and/or an atomic force microscope,performing local checks of topographic and/or electrical conductivity ofthe treated surface 5.

[0122] Obviously, it is possible to keep only certain detecting means,according to the applications contemplated as well as the nature and theaccuracy of the results desired.

[0123] In operation for an interaction without penetration of thesurface 5, during a local structural modification step 18 (FIG. 3), thefollowing operations are performed in succession. The beam 41 ofmulticharged positive ions is generated by means of the ion source 20,an ionic specie of this beam 41 is selected by the means of application21 of the magnetic field 33, the beam 42 obtained is guided towards thesurface 5 by the means of application 23 of the magnetic field 36 byconducting direct position control by the system 22 and spatiallocalisation by the collimators 25 and 26, then the beam 42 is sloweddown.

[0124] When the ions of the beam 42 are close enough to the surface 5,they start to interact with said surface. The ions may capture theelectrons of the wafer 1 as soon as they reach a capturing zoneextending up to a distance d above the surface 5. Thus, when an ion 40penetrates the capturing zone, it interacts with a portion 46 of thissurface 5 delineating approximately a disk with diameter D havingcontours at a distance d from the ion 40, as represented on FIG. 5.

[0125] The ion 40 attracts and extracts superficial electrons from theportion 46 as it approaches in the capturing zone. This approach iscontrolled by adjusting the kinetic energy of the ion 40 thanks to theelectrical deceleration field. The ion 40 captures electrons whichtransforms said ion into a hollow atom. This hollow atom is thenbackscattered without contact by a trampoline effect when theexperimental conditions allow it and it is directed towards thedetection surface 28.

[0126] The extraction of electrons from the surface 5 causes localrupture of the crystalline structure of the diamond, responsible for itsvery high resistivity. This physical phenomenon causes local change ofelectrical properties, which leads to the formation of a conductivelayer inside the very insulating diamond layer 3.

[0127] The local structural modification is based upon the successionand the repetition of four operations 13-16 (FIG. 3), controlled by thetreatment unit 29.

[0128] In a first operation 13, one detects he arrival on the detectionsurface 28 of the particles issued from the surface 5, the emission, inthe vicinity of the surface of photons, preferably of a spectrum of Xrays or of electrons, by means of the measuring device 49 and/or one orseveral signals generated by the detection system 45. The treatment unit29 receives thus one or several signals corresponding to thesedetections. In a second operation 14, one then interrupts the arrival ofthe beam 42 on the target, by controlling the closing of the shutter 24.In a third operation 15, one then triggers the controlled motion of thetranslator 27, over a distance advantageously in the order of thenanometre. In a fourth operation 16, it controls the opening of theshutter 24, so that the beam 42 can again reach the surface 5.

[0129] By repeating the operations 13 to 16, one generates a localstructural modification in the zones corresponding to the presetconductive portions. One can thus obtain the wafer 1A with conductiveislands 6 or the wafer 1B with conductive lines 7, by a succession oflocal interactions a very well defined spots.

[0130] Preferably, one checks at a later stage 17 the surface 5 forelectrical conductivity locally, by means of tunnel effect and/or atomicforce microscopes.

[0131] In order to implement the method with penetration of the surface5 by the ions of the beam 42, one can deactivate the deceleration means.The interaction between each ion 40 and the surface 5 is potential in afirst step (remote interaction), then kinetic in a second step(penetration of the surface 5). The pieces of information used come fromthe detection system 45 and from the measuring device 49, as well aspossibly from the detection surface 28, whereas atoms or ions arerecovered after expulsion from the surface 5.

[0132] The local structural modification device detailed above can alsobe used for a random treatment, whereas the treatment unit 29 thensimply controls movements of the translator 27 without taking intoaccount the detection results. The shutter 24 is then deactivated. Suchan implementation is advantageous for speed reasons, even if it does notenable to control the locations of the conductive zones on the surface5. Preferably, the ions of the beam 42 are then sent at the same timeinto different spots on the surface 5 (rather than one after another).

[0133] Moreover, the local structural modification device can enable totreat fractions 9 of the surface 5, in order to provide a wafer of thetype 2C.

1. A method for treating a surface (5) wherein: ions (40) are produced,each having at least three positive charges, and a beam (42) of saidions is sent towards the surface (5), characterised in that the beam(42) is sent towards a diamond surface (5), in order to make at leastone zone (6, 7, 9) of the surface (5) conductive under the effect ofsaid ions (40), and in that each ion has a charge, a kinetic energy andan incidence such that it generates local structural modifications ofthe surface (5), each having a surface area greater than 4 atomicsurfaces and preferably 10 atomic surfaces, of said diamond and smallerthan 22,500 nm².
 2. A treatment method according to claim 1,characterised in that said beam (42) is sent in order to form at leastone conductive island (6) with a diameter smaller than 150 nm.
 3. Atreatment method according to claim 2, characterised in that saidconductive islands (6) have a diameter smaller than 10 nm and preferablyranging between 2 and 6 nm.
 4. A treatment method according to claim 3,characterised in that said islands (6) are used as one election tanks.5. A treatment method according to claim 2, characterised in that saidconductive islands (6) are used as reservoirs for replenishing coldcathodes.
 6. A treatment method according to claim 1, characterised inthat the beam is sent in order to form conductive lines (7) delineatinginsulating patterns (8).
 7. A treatment method according to claim 1,characterised in that said beam (42) is sent in order to make at leastone fraction (9) of the diamond surface (5) conductive.
 8. A treatmentmethod according to any of the previous claims, characterised in thatlocal structural modification is performed on a random basis.
 9. Atreatment method according to any of the claims 1 to 8, characterised inthat the ion beam (42) is sent so that it contacts the surface (5) andpenetrates said surface.
 10. A treatment method according to claim 9,characterised in that said ions with an initial kinetic energy rangingbetween 5 eV/q and 500 keV/q are generated.
 11. A treatment methodaccording to any of the claims 1 to 8, characterised in that the beam(42) is applied a deceleration voltage close to the surface (5) in orderto confer to the ions (40) of the beam (42) a controlled average speed,whereas said ions (40) extract electrons from the diamond atoms withoutcontacting the surface (5) and therefore modify the links between saidatoms.
 12. A treatment method according to claim 11, characterised inthat said ions are slowed down so that they have close to the surface(5) a kinetic energy ranging between 5, 10⁻² eV/q and 5 eV/q.
 13. Atreatment method according to any of the previous claims, characterisedin that the diamond surface (5) is a monocrystalline diamond surface.14. A treatment method according to any of the claims 1 to 12,characterised in that the diamond surface (5) is a polycrystallinediamond surface, preferably obtained by a CVD technique (Chemical VapourDeposition) or a HPHT technique (High Pressure High Temperature).
 15. Atreatment method according to claim 14, characterised in that thediamond surface (5) is a layer (3) deposited on a substrate (2).
 16. Atreatment method according to any of the claims 1 to 12, characterisedin that the diamond surface (5) is an amorphous carbon sp3 surface. 17.A treatment method according to any of the previous claims,characterised in that the diamond surface (5) is passivated by an atomicmonolayer (4), preferably made of hydrogen or oxygen.
 18. A diamondsurface (5A) delineating conductive islands (6) with a diameter greaterthan 2 and preferably to 3 atomic distances and greater than 10 nm. 19.A diamond surface according to claim 18, characterised in that saidislands (6) have a diameter ranging between 2 and 6 nm.
 20. A diamondsurface according to any of the claim 18 or 19, characterised in thatsaid islands (6) have conductive properties similar to those ofgraphite.
 21. An application of the surface (5A) according to any of theclaims 18 to 20 to micro-electronics, wherein one uses said conductiveislands (6) as one election tanks.
 22. An application of the methodaccording to any of the claims 1 to 17 to the production of coldcathodes, notably for flat screens.